The present invention is generally related to data muting techniques in voice communications systems, and more particularly to an improved data muting method and apparatus that is particularly well adapted for use in radio communications systems.
In the prior art, data muting in receivers of a voice communications systems typically has been accomplished by detecting the presence of a data signal and then muting the output of the receiver so that it is not heard. Many different techniques exist for detecting the presence of the data signal, such as, for example, those described in U.S. Pat. Nos. 3,758,860, 3,939,431, 4,197,502, 4,233,565 and 4,229,822. Since each of the foregoing prior art techniques requires the reception of several bits in order to detect the data signal, a short data burst is always passed to a listener. Since the peak-to-peak signal level of the data signal is very high for reliability reasons, the data bursts are very loud. During peak periods of data traffic in such communications systems, these data bursts are very annoying to a listener.
In receivers of other communications systems, the output of a receiver is muted for a fixed time period that is long enough to include the data signal. Since the fixed time period must be made long enough to accomodate system delays and the longest data signal, voice communications immediately following the data signal may also be muted. Therefore, there is a long felt need for a data muting method and apparatus that mutes the entire data signal without muting the following voice communications.